Automatic machining has been considerably developed by application of NC (or numerically controlled) machine tools or robots etc. That is, an unmanned operation has been realized in a machining center unit such as a machining center having a multi-sided pallet conveyer.
However, flow of materials in a machine shop, that is, a discharge of works from a warehouse, transfer and delivery of the works from the warehouse to the machine tools, and discharge of works after machining have been performed by workers. Such workers may have to handle heavy materials which continually cause possible danger and limit operational efficiency. In such a machine shop, various shapes of works to be machined may have to be handled. It is very troublesome to convey and precisely position such various works on the tables of the machine tools using the, skills and experiences of such workers.
Thus, automation of material-flow in a machine shop, by which various works are automatically conveyed and positioned and the works after machining are automatically conveyed, is required, with such various shapes of works being delivered onto the machine tools at high accuracy.